/Engine/Plugins/Experimental/TetMeshing/Source/TetMeshing/Public/Generate/IsosurfaceStuffing.h
In sum, the bits of an Edge ID are laid out as: [Bits 53-50: 'Tag' indicating which edge] [Bits 48-0: Point ID for a grid point attached to the edge] And Point ID is laid out as: [Bit 48: bIsCenter flag] [Bits 47-32: Z coord] [Bits 31-16: Y coord] [Bits 15-0: X coord]
static constexpr int64 GetMajorAxisEdgeTag ( int64 Axis )